Wikipedia
Grade-taking is a social system under which individuals rise in status and authority by performing a series of ceremonies, typically involving the killing of valuable pigs. Grade-taking was the system of leadership in pre-colonial societies of northern Vanuatu, and is still actively practiced in some areas.
With each grade, a participant acquires a named rank, and the right to display certain insignia or perform certain rituals. The specifics vary between cultures. Lower grades are typically taken in one's youth and involve the killing of only one or a few low-value pigs. However, at the highest grades hundreds of pigs may be killed, including valuable 'tusker boars'. Although there is a clear hierarchy of grades, they do not necessarily need to be taken in strict sequence, and individuals with sufficient resources may occasionally skip grades and move directly to higher levels.
Grade-taking is primarily a male activity, but in some areas there are parallel grade-taking systems practiced by women.